Folding devices of the above-described type are generally known. Folding is performed at full paper speed by means of a rotary folding blade that projects from the surface of a rotating drum, and the tip of said folding blade pushes the print copy or pack of print copies to be folded into two folding rollers rotating in opposite directions. Misfolding at high paper speeds is a disadvantage of these devices. This causes damage due to the whipping effect that occurs at the trailing ends of the print copies.
West German Offenlegungsschrift No. 28,46,191 discloses a process in which the packs of copies to be printed are distributed between two analogous folding devices, so that the folding speeds are cut in half, which is said to lead to a reduction of the whipping effect. However, a folding device based on this process is very expensive, because it requires two folding devices for the additional fold.